1. Field of the Invention
The present invention relates to an electronic device such as an electronic camera which is powered by battery, more specifically, to an electronic device in which different types of batteries can be selectively used as a power source.
2. Description of the Related Art
A cylindrical primary CR-V3 lithium battery (manganese dioxide/lithium battery) which is interchangeable with two AA-size cells (two primary or secondary AA-size cells), has been available on the market in recent years. Furthermore, various cameras for which one or more CR-V3 batteries are available as a power source have been developed in recent years. Primary lithium batteries are high in weight energy density and volume energy density, and are accordingly suitable as a power source for high-power consumption electronic devices such as digital cameras. FIGS. 11 and 12 each show an outward appearance of a CR-V3 battery.
Since the CR-V3 battery is accommodated in a battery chamber, in which two AA-size cells can be accommodated, there is a possibility of one CR-V3 battery and two or more AA-size cells being intentionally or unintentionally accommodated together in a battery chamber of a camera in which four or a larger even number of AA-size cells can be accommodated to serve as a power source of the camera. For example, in a camera using four AA-size cells, there is a possibility of two AA-size cells and one CR-V3 battery being accommodated in the battery chamber and subsequently being used in such a state. Additionally, there is a possibility of four AA-size cells which includes both primary and secondary cells being accommodated in the battery chamber and subsequently being used in such a state.
Accordingly, if either a combination of two or more AA-size primary cells and at least one CR-V3 battery, or a combination of two or more AA-size primary cells and two or more AA-size secondary cells are accommodated together in a battery chamber of a camera which can accommodate at least four or a larger even number of AA-size cells, the AA-size primary cells may be forcibly charged accidentally due to a difference in voltage between the AA-size primary cells and the CR-V3 battery or the AA-size secondary cells, even though the AA-size primary cells are non-rechargeable batteries. If a voltage for battery charging is applied to the AA-size primary cells, the AA-size primary cells may result in battery fluid leak, heat generation, damage and/or explosion, which is dangerous. Such improper use of batteries cannot be sufficiently prevented from occurring even if an instruction manual calls attention to such a danger.